The present invention relates to a charging receptacle for use in an induction type charging apparatus for charging a battery of an electric vehicle or the like.
Conventionally, a conduction type charging apparatus and an induction type charging apparatus have been utilized for charging batteries of electric vehicles. The conduction type charging apparatus has a contact type connection terminal for directly connecting a power supply positioned external to a vehicle with a battery equipped in the vehicle. In contrast, the induction type charging apparatus has a non-contact type connection terminal for connecting a power supply with a battery through electromagnetic induction. The induction type charging apparatus is less susceptible to a contact failure. In addition, the induction type charging apparatus is smaller than the conduction type charging apparatus, so the induction type charging apparatus has drawn particular attention in recent years.
FIG. 5 illustrates a connection terminal of a conventional induction type charging apparatus. The connection terminal has a charging paddle 61, and a charging receptacle 71 for receiving the charging paddle 61. The charging paddle 61 is connected to a cable 62 extending from an external power supply station (not shown). The charging receptacle 71 is equipped in an electric vehicle, and connected to a battery also equipped in the vehicle.
The charging receptacle 71 has an enclosure 75, an inserting hole 72 formed through the enclosure 75, a power receiving core 73 accommodated in the enclosure 75, and a power receiving coil 74 contained in the enclosure 75 and wound around the power receiving core 73. For reducing the time required for charging, i.e., for achieving rapid charging, some charging apparatuses for electric vehicles use high frequencies and high power. For example, a charging apparatus that uses 430 volts and high frequencies (100 kHz to 370 kHz) to produce power of 80 kilowatts has been developed. In regard to this type of charging apparatus, the charging receptacle 71 is accommodated in the enclosure 75, which is shielded against the noise to prevent external noise of radio waves, electromagnetic waves and so on from entering the connection terminal, and to prevent emission of noise due to a large current at a high frequency handled by the connection terminal itself.
The charging paddle 61 has an distal end 63, which contains a power transmitting core 64 and a power transmitting coil 65 wound around the power transmitting core 64. For supplying power, the charging paddle 61 is inserted into an inserting hole 72 of the charging receptacle 71 to place the power transmitting coil 65 upon the power receiving coil 74. Then, the power supply station passes a current (alternate current) through the power transmitting coil 65 to induce power in the power receiving coil 74.
A plurality of ventilation holes 76 are formed around the inserting hole 72 of the enclosure 75 of the charging receptacle 71 for introducing external air. When heat is generated during charging from the power transmitting coil 65 of the charging paddle 61 and the power receiving coil 74 of the charging receptacle 71, external air is introduced through the holes 76, and is exhausted to the outside by a cooling fan 77 on the opposite side of the enclosure 75. In this way, the heat is discharged to the outside.
The charging apparatus also includes an interlock function for starting conduction after confirming that the charging paddle 61 is securely inserted into the charging receptacle 71; a function of determining a charging rate (power value) from a power supply station external to the vehicle based on a vehicle determination such as the voltage of an on-vehicle battery or the like; and a function of charging while monitoring condition such as the liquid temperature of the on-vehicle battery. Suitable charging conditions are set through communications of information between the vehicle and the external power supply station. Consequently, the power supply station external to the vehicle supplies appropriate power for the preferred charging conditions to the power transmitting coil 65 of the charging paddle 61 through the cable 62.
The transmission and reception of the information are performed by a communication unit 78 attached on the enclosure 75 of the charging receptacle 71 and a communication unit 66 contained in the charging paddle 61 through wireless communications. The communication unit 78 is accommodated in a noise shielded case 79 for preventing malfunctions due to radio waves of portable telephones or other devices.
However, due to the structure in which the communication unit 78 is accommodated in the case 79 attached on the enclosure 75 of the charging receptacle 71, the resultant charging receptacle 71 is large. This is a problem for electric vehicles, which are required to be smaller.
In addition, a space must be provided for insulation between the noise shielded case 79 of the communication unit 78 and a current-carrying part of a communication circuit. This also increases the size of the communication unit 78.
During charging, the power receiving coil 74 and the power transmitting coil 65 generate heat. Then, the heat is conducted from the enclosure 75 of the charging receptacle 71 to the communication unit 78 carried on the enclosure 75 of the charging receptacle 71 to elevate the temperature of the communication unit 78. As a result, the communication unit 78 become unstable due to the elevated temperature, particularly when the atmospheric temperature is high as in summer.
Also, for securely inserting the charging paddle 61 into the charging receptacle 71 when the battery is charged, guiding members (not shown) must be formed on the top and bottom within the inserting hole 72 of the enclosure 75 of the charging receptacle 71. The formation of the guiding members also increases manufacturing costs.
Moreover, the enclosure 75 of the charging receptacle 71 is loaded with the weight of such parts as the power receiving core 73 of the charging receptacle 71 accommodated therein, the power receiving coil 74, the cooling fan 77, and other parts. Also, when the charging paddle 61 is inserted into the enclosure 75, and the enclosure 75 is required to have strength enough to withstand this weight. In addition, an operator may inadvertently twist the charging paddle 61 when inserting or removing the charging paddle 61, so the enclosure 75 is also required to withstand such torsion. It is therefore necessary to form the enclosure 75 of a strong material, thereby increasing manufacturing costs.
The communication units 66, 78 used in the charging paddle 61 and the charging receptacle 71 wirelessly communicate with each other. The frequency band of radio waves available to the wireless communication differs from one country or area (zone) to another. Therefore, for commercializing the charging paddle 61 and the charging receptacle 71, a plurality of different types must be manufactured to adapt to the available frequency bands in respective countries and areas. Thus, the provision of a large number of types increase the manufacturing costs of the charging receptacle 71.
It is an object of the present invention to provide a charging receptacle which is capable of maintaining a good shielding capability against electromagnetic noise while reducing the size.
It is another object of the present invention to provide a charging receptacle which is manufactured at a low cost.
To achieve the above objectives, the present invention provides a charging receptacle for an electromagnetic induction type connection terminal for connecting a power supply station with a battery for charging the battery. The connection terminal has a charging paddle that plugs into the charging receptacle. The charging paddle has a primary coil supplied with a current from the power supply station. The charging receptacle includes a secondary coil connected to the battery, an enclosure for accommodating the secondary coil, and a communication unit for communicating information with the charging paddle to control the charging. The secondary coil produces an inductive electromotive force when the primary coil is supplied with current from the power supply station and when the charging paddle is plugged into the charging receptacle. The enclosure forms a shield against electromagnetic waves. The communication unit is within the enclosure.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.